Bret Stetka in Scientific American:
About 2,500 years ago something changed the way humans think. Within the span of two centuries, in three separate regions of Eurasia, spiritual movements emerged that would give rise to the world's major moral religions, those preaching some combination of compassion, humility and asceticism. Scholars often attribute the rise of these moral religions—Buddhism, Judaism, Islam, Hinduism and Christianity included—to population growth, seeing morality as a necessary social stabilizer in increasingly large and volatile human communities. Yet findings from a recent study published in Current Biology point to a different factor: rising affluence.
The authors investigated variables relating to political complexity and living standards. Affluence emerged as a major force in the rise of moral religion, in particular, access to energy. Across cultures moral religions abruptly emerged when members of a population could reliably source 20,000 calories of energy a day, including food (for humans and livestock), fuel and raw materials. “This number appears to correspond with a certain peace of mind,” says lead author Nicolas Baumard, a research scientist at École Normale Supérieure in Paris. “Having a roof over your head, not feeling like the world is full of predators and enemies, knowing that you'll have enough to eat tomorrow.” As Baumard points out, psychology research shows that affluence appears to influence our motivations and reward circuitry away from short-term gain to also considering the benefits of long-term strategy. In other words, with a steady energy supply, we had more time to cooperate, cultivate skills and consider consequences. Affluence also allowed more time for existential pondering: maybe we have some greater moral responsibility; perhaps life has a purpose.
Baumard acknowledges that moral and ascetic qualities probably existed in humans before the major religions emphasizing them.